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III. Study Goal., Objective., and End product Goal -- Daea from ehis study will be used as part of an annual assessment of reproduction and recruitmene of Colorado squawfish (and other fishes) so thae various hypotheses regarding the affects of modified operation of Flaming Gorge Dam can be evaluated. Information will facilitate assessment of relationships between relative reproductive success and annual flow regimes (specifically flow releases from Flaming Gorge Dam) and proy1de a relative measure of input of fish larvae into downstream nursery habitats. Objective. -- 1.) To document timing and duration of spawning by Colorado squawfish (and oeher fishe.) as mea.ured by capture of drifting larvae. 2.) To determine peaks in abundance of transported Colorado squawfish larvae during the spawning season. 3.) To determine the relative abundance of Colorado 'squawfish larvae transported from spawning areas in the 101l8r Yampa River CYampa Canyon) and the lower Green River (Grey and Desolation canyon.) into downstream nur.ery habitats (Jensen-Ouray and Kineral Bottom areas, respectively). Some A..umption. -- 1.) Results of previous studies on young Colorado squawfish in the Green River sy.t_ provide accurate ba.eline information on movements and distribution. 2.) Efforts of this .tudy and of other PaFRI studies will be sufficient to provide accurate, more-detailed information on distribution and r.lativ. abundance of young Colorado squawfi.h. 3.) Nost larva. are produc.d in two spawning areas (i.e., low.r Yampa ,'Canyon and Grey and De.olation canyons) and mo.t are transported into the two nur.ery ar.a. (i.... Jen.en-OUray and Kin.ral Bottom, respectively)_ In order to more rigorou.ly a.se.. these asswnption.. use of marked larva. and ac1di.tional drift-net station. (e.g., upstrelllll of the Grey-Desolation spawning ar.a and downstream of the Min.ral Bottom nursery area) and seine sampling (throughout the Green River and covering a greater temporal period; other than what 18 proposed under Core-Research Study No.2 would be nec..sary. However, we beli.ve that previous studies have provided accurate baseline information, .pproval to use marked larvae in the Green River ay.t_ i. probably not forthcoming, and logistics and costs associat.d with additional sampling would be prohibitive. Information 'from hypoth....-te.ting study 5 (hypothe.e.-te.ting Task 5; especially the ageing and growth W9rk) will facilitate a.sessment of these a..umptions. . BDel Product -- A s~ry report will be .ubatitteel at the end of each fi.cal year. At the enel of the 5-year effort, information will be integrated with reau1ta of other Flaming Gorge inveatigations. IV. Study Ar.a: Lover Yampa River (ju.t up.tream of the Y:ampa-Green River confluence, Echo Park, Oinosaur National Nonument), Colorado, and lower Green River (possibly near the town of Green River), Utah. Flaming Gorge Studies A3